1. Field of the Invention
The present invention relates to an optical sensor apparatus, in particular to an optical sensor apparatus for infrared radiation for use in electronics equipment such as a video tape recorder or a portable camcorder with a wireless remote commander.
2. Background of the Invention
FIG. 6 shows an all-directional optical sensor apparatus which has been used for the electronics equipment. The sensor apparatus includes a sensor portion 10 and an all-directional prism 20 arranged above it. As shown in FIG. 8, the sensor portion 10 has a sensor surface 12 which receives the rays through the all-directional prism 20.
The sensor surface 12 is formed by a sensor element such as a photo-diode, so that, among the rays of incidence to the whole sensor apparatus, only the rays received by the sensor surface 12 can be transformed into an electric signal. This all-directional sensor apparatus can be applied as a sensor apparatus for detecting the infrared radiation from a wireless remote commander, so that the electrical output signal can be generated by receiving the infrared radiation as an input signal.
FIGS. 7A and 7B show an all-directional prism which has been used in the sensor apparatus. The all-directional prism 20 is made of, for example, a light transmissible resin having a polygon post shape with a hollow cone formed in a top surface. In an example shown in FIGS. 7A and 7B, an octagon post having a top surface 22, a bottom surface 26 and eight side surfaces 24 is formed with an octagon cone formed in the top surface 22. The octagon cone surface 28 work as a reflector 30. The preferable solid angle of octagon cone is 90 degrees as shown in FIG. 7B.
FIG. 8 shows optical paths of rays received by the all-directional optical sensor apparatus. The rays received through side surfaces 24 of the all-directional prism 20 are reflected by the reflector 30 and then become incident on the sensor surface 12 of sensor portion.
FIG. 9 and FIG. 10 respectively show other examples an all-directional prism 20. The example shown in FIG. 9 has a cylindrical post with a hollowed-out section in the shape of a circular cone having a solid angle of 90 degrees. The other example shown in FIG. 10 has a cube with an octagon trapezoidal cone formed in a top surface. The octagon trapezoidal cone is made of a bottom surface 28A and eight cone surfaces 28. Each of the cone surfaces 28 works as a reflector 30 for rays passed through the side surfaces 24 the all-directional prism 20.
In electronics equipments for both indoor and outdoor uses, such as a camcorder, the above mentioned optical sensor apparatus is controlled by a wireless remote commander with the use of infrared radiation. When using the equipment outdoor with the wireless remote commander using the infrared remote control signal, the area for remote control operation in its outdoor use becomes smaller than in its indoor use. The sun beam causes this problem so that the sensitivity of the optical sensor apparatus with the infrared radiation may be worsened. Therefore an effective distance for the remote control signal from the remote commander to reach at the optical sensor becomes shortened.
Improvements have been made by putting a silver colored film on the cone surface 28 in FIG. 8 in order to shield the optical sensor apparatus from the sun beam or light. The optical sensor will then receive only the signal rays of infrared radiation from the wireless remote commander. The film can be put on the cone surface 28 which is forming an inner surface of the hollow in the all-directional prism 20. With the placement of the film, the sun beam 34 may be excluded from entering into an upper portion of the prism 20 and only the signal rays 32 may be received through the side surfaces 24 of prism 20.
However, the placement of the film on the cone surface 28 cannot completely exclude the sun beam from entering the upper portion of the prism. Consequently, the effective distance has been still restricted for the infrared radiation as an input signal from the wireless remote commander.